Automatically operable safety landing switch for airplanes



July 4, 1944. J. A. DANN 2,352,692

AUTOMATICALLY OPERABLE SAFETY LANDING SWITCH FOR AIRTLANES Filed Feb. 26, 1941 INVENTOR Jase/v4 4. D/Q/v/v Patented July 4, 1944 UNITED STATES PATENT OFFICE AUTOMATICALLY ormanm SAFETY mnmo swrron row AIRPLANES Joseph A. Dana, Milwaukee, Wis.

Application February 26, 1941, Serial No. 380,658

' 4 Claims.

My invention relates to improvements in automatically operable safety landing switches for airplanes.

The object of my invention is to provide means whereby if an airplane tends to "nose over or somersault when making a landing. the ignition circuit will be automatically interrupted, thereby eliminating fire hazards.

In the drawing:

Figure l is a fragmentary view illustrating the forward end portion of an airplane equipped with one embodiment of my invention.

Figure 2 is a detail view, partly in section, exposing one embodiment of my auxiliary safety switch and associated connections.

Figure 3 is an enlarged view of the safety switch, its housing being illustrated in section.

Figure 4 is a view, partly in section and partly in elevation, showing a modified form of my safety switch mechanism, in which the switch is located within the nose of the fuselage and operated from an exterior arm.

Figure 5 is a detail of the switch operating arm shown in Figure 4.

Like parts are identified by the same reference characters throughout the several views;

For the purposes of my invention, the nose portion ID of the fuselage of any ordinary airplane may be provided with a forwardly and downwardly projecting arm ll of insuflicient length to reach the ground during normal landings. This arm preferably has the form of a tapering tube, and in Figures 1 and 2 it is shown with a cylindrical head portion I! at its lower end, within which a safety switch may be located, and connected with the ignition circuit by suitable wiring extending through the arm, preferably in the form of a cable l4, and connected in a main ignition circuit represented by the wires l5 and I6 and the branch wires l1 and I8 leading through the cable to the safety switch.

As shown in Figure 3, these wires are respectively connected to contact terminals 20 and 2| within the cylindrical head portion l2, and these terminals normally bear upon a contact ring 22 mounted upon an insulating sleeve 23 carried by the shank 24 of a push button 25. push button is driven inwardly, the contact ring 22 will move away from the terminals 20 and 2|, and the latter will enter and become socketed in the annular groove 21 in the insulating sleeve 23, thus breaking the circuit.

The push button 25 will preferably be normally protected from contact with grass or weeds by a frangible or flexible housing 3', but when this When the housing is brought forcibly into contact with the ground, its strength will be insufficient to prevent. the push button from being driven inwardly to the circuit breaking position. If the housing is made of glass it will be fractured. If it is made of rubber or fabric, it will simply yield and allow the necessary pressure to be applied to the push button in order to interrupt the circuit.

In Figure 2, the main switch ordinarily employed for closing the ignition circuit is indicated at 34. Preferably an auxiliary, manually operable switch may be mounted on the instrument board 35 immediately below the main switch 34, as indicated at 3B. When this switch is manually closed by means of its operating lever 31, it cross connects the wires l1 and I8, thereby again closing the ignition circuit notwithstanding the interruption at the lower end of the arm ll, thus enabling the motor to continue to function after the danger of nosing over" is past. Of course, if the airplane turns over, there will be no occasion for operating the manually controlled switch at 36.

In Figure 4 I have illustrated an embodiment of my invention, in which an arm Ha may be employedmerely for the purpose of controlling a safety switch located within the nose of the fuselage, or within any other housed portion of the airplane. Any suitable operating mechanism may be employed, but in the construction illustrated, the arm Ila is provided with a frangible member or ring 40, which projects beyond the end of the arm I la and is provided with an aperture through which a cord or cable 4| may extend. The ends of this cable are passed through apertures in the end of the arm H11. and connected with a disk or cross piece 42, to which a cable 43 is attached.

The cable 43 extends through the wall of the fuselage and connects with a slide 44 mounted in a frame 45, supported by a bracket 46 from the wall H! of the fuselage nose. The slide 44 is provided with an insulating member or sleeve 23a which supports a contact ring 22a, which normally connects the terminals 20a and Zlw for closing the auxiliary branch wires Ila and Illa.

A compression spring 48 is interposed between the bracket 46 and the end of the slide 44, and urges the slide inwardly in a direction to carry the contact ring 22a out of circuit closing position and bring the insulating sleeve 23a into circuit breaking position.

However, the spring is normally prevented from functioning by means of the cable 43 and its connection with the frangible or deformable member ll. Should the latter become broken or deformed, the tension will be released and the spring will immediately react and push the slide as to circuit breaking position.

It will be understood that the safety arm II (or H will be made sufliclently short to allow a normal landing of the airplane without having any portion of the arm contact with the ground, and therefore without interrupting th ignition circuit. I

While I have shown arms II and Ho as directly connected with the nose of the fuselage, it is immaterial to whatportion of the airplane these arms are attached if the free end portion is supported in front of'the landing wheels and at a sufiicient elevation to avoid contact with the ground during normal landings.

It will also be obvious that any switch operating mechanism in a similar position with refcrence to the landing wheels and the nose of the fuselage may serve as an equivalent for the switch operating mechanisms hereinbefore specifically illustrated and described, and that neither the illustrations nor the speciflcation are intended to limit the scope of the invention to the par-' ticular mechanisms disclosed.

I claim: I i. In an airplane having ordinary landing wheels, a power operated means, and a fuselage having an ignition circuit for said power operated means, said circuit including an ignition cut-out switchand having an exterior arm pro- Jecting forwardly and downwardly in front of the forward landing wheels, with its lower end portion at a 'sumcient elevation to be out of contactwith the ground during normal landing operations, at least-an outer end portion of said am being displaceable, and means connecting said displaceable portion with saldswitch for actuating said switch to break the ignition circuit. said arm portions being positioned to be operated by displacement when the fuselage is sufflcientiy tilted abnormally forwardly over the landing wheels in movements over the earth to cause engagement of said portion with the earth and thereby to displace the said portion of said arm 2. 'I'he combination with anrairplane having ordinary landing wheels, a power operated means,

and a fuselage with normally operating parts of an ignition circuit for said power operated means housed therein, of an exterior hollow arm pro- Jecting forwardly and downwardly in front of the forward landing wheels, having a displaceable lower end portion located at a sufiicient elevation to avoid contact with the ground during normal landings, circuit breaking mechanism having an actuating member housed in said arm and disposed in the path of movement of said displaceable portion to be actuated thereby, when said portion is actuated by contact with the ground, said mechanism being so located as to be operative to break said circuit when the arm portion and member are displaced by pressure contact with the ground during abnormally forwardly tilting movements of the fuselage on the ground.

3. In an airplane having ordinary landing wheels, a power operated means, and a fuselage having an ignition circuit for said power operated means, said circuit including a circuit breaking member located exteriorly of the fuselage in front of and above the forward landing wheels, and a protecting arm for said member extending forwardly and downwardly from the fuselage with its lower end normally out of contact with the ground during landing operations, the lower portion of said arm being dlsplaceable by pressure contact with the ground when the fuselage is approaching a nose-over position during a landing operation and connected with said member for the actuation thereof to break said circuit when said arm portion is displaced.

4. In .an airplane having ordinary landing wheels, a power operated means and a fuselage having an ignition circuit for said power operated means, said circuit including a branch leading to the exterior of said housing, circuit breaking mechanism associated with said branch and having an operating member normally located above the ground level in movement of the airplane on the ground but in position for contact with the ground during movement thereover only when the nose of the airplane is relatively forwardly tilted abnormally, and an auxiliary manually operable switch within the fuselage for establishing a shunt across the circuit breaking mechanism and again closing the ignition circuit after said circuit breaking mechanism is operated.

JOSEPH A. DANN. 

